Mozambique IACM Private Pilot (PPL-A) key terms

A set of rules allowing a pilot to operate an aircraft mainly by looking outside for traffic and terrain, provided minimum visibility and cloud separation are maintained. It also defines when ATC clearance is required.

The minimum flight visibility and distance from cloud that must exist for flight under visual flight rules. Values vary with airspace class and altitude and are published in the national aviation regulations.

An authorisation from air traffic control that lets a pilot fly under visual flight rules inside a control zone when the weather is below normal VMC minima, usually subject to remaining clear of cloud and in sight of the surface.

Controlled airspace extending upwards from the surface around an aerodrome, established to protect arriving and departing traffic. A clearance is normally needed to enter it, and it commonly coincides with the aerodrome traffic zone.

Airspace of defined dimensions around an aerodrome used to protect aerodrome traffic. Pilots must follow specific joining and reporting procedures, and radio contact is typically required before entry.

A surface of constant atmospheric pressure referenced to a standard pressure setting of 1013.2 hPa and expressed in hundreds of feet. Aircraft flying at higher altitudes use flight levels so that all altimeters read consistently.

The altitude, published for a given area, at which a pilot changes the altimeter from local pressure setting to standard pressure and begins referring to flight levels. Below it, altitude above mean sea level is used.

The altimeter setting that, when entered in the subscale, makes the altimeter read altitude above mean sea level at the aircraft's position. It is obtained from aerodrome or area forecasts and reports.

The altimeter setting that makes the altimeter read height above a specified reference point, usually the aerodrome. It is used in some traffic patterns and approach procedures to show height above the runway.

An authorisation issued by air traffic control for an aircraft to proceed under specified conditions. It does not relieve the pilot in command of responsibility for terrain clearance, traffic avoidance or safe operation of the aircraft.

The mandatory repetition by a pilot of safety-related clearance elements such as route, level, heading, speed and frequency. It lets the controller confirm that the instruction was received and understood correctly.

A radio message giving the aircraft's identification, position, time, altitude or flight level and next position with estimated time. It is required at compulsory reporting points and helps controllers maintain separation.

A rule assigning cruising levels according to magnetic track: tracks from 000 to 179 degrees use odd levels, and tracks from 180 to 359 degrees use even levels. It separates opposing traffic in cruise.

A level-allocation rule, used in some airspace, that assigns cruising levels according to four magnetic track quadrants. Each quadrant uses a different series of levels so that opposing and crossing traffic are separated.

A condition in which the body's tissues receive insufficient oxygen. In aviation it can result from high altitude, reduced cabin pressure or breathing difficulties, and it impairs judgement and vision before the pilot notices the symptoms.

The period after loss of adequate oxygen supply during which a person can still take corrective action before becoming incapacitated. It shortens rapidly as altitude increases and is reduced by cold, fatigue and exertion.

Excessively rapid or deep breathing that lowers carbon dioxide in the blood, causing dizziness, tingling and confusion. Its symptoms resemble hypoxia, and treatment is to slow the breathing rate and breathe normally.

A pilot's mistaken perception of the aircraft's attitude or motion, usually caused by conflicting or absent visual cues in cloud or darkness. Recovery depends on trusting the flight instruments rather than physical sensations.

The inner-ear organs that sense acceleration and rotation, helping maintain balance. They can produce false sensations during sustained turns or acceleration, so pilots must rely on instruments in poor visual conditions.

The equivalent altitude inside a pressurised aircraft cabin, maintained below the aircraft's actual altitude for comfort and oxygen supply. If pressurisation fails, cabin altitude rises and oxygen equipment may be required.

Illness caused by inhaling carbon monoxide, often from engine exhaust leaking into the cabin. It causes headache, drowsiness and impaired judgement, and is suspected when symptoms improve after breathing fresh air or oxygen.

A reference model of the atmosphere with sea-level pressure 1013.25 hPa, sea-level temperature 15 degrees Celsius and a fixed lapse rate. It is used to compare and calculate aircraft and engine performance.

The altimeter setting that, when entered in the subscale, makes the altimeter read altitude above mean sea level at the aircraft's position. It is obtained from aerodrome or area forecasts and reports.

The altitude in the standard atmosphere at which the air density equals the actual density at a location. High temperature, high elevation and high humidity raise it and reduce aircraft and engine performance.

The altitude indicated when the altimeter is set to standard pressure 1013.25 hPa. It is used with temperature to calculate density altitude and true performance figures.

The rate at which temperature decreases with increasing height in the atmosphere. The standard average value is about 2 degrees Celsius per 1000 feet, though the actual rate varies with moisture and stability.

The difference between air temperature and dewpoint temperature. A small spread indicates air close to saturation, so cloud, fog or carburettor icing becomes more likely as the spread decreases.

Ice forming in a carburettor, most often from fuel vaporisation and pressure drop rather than from visible moisture. It can occur at moderate outside temperatures and is countered with carburettor heat.

A condition in which the wing exceeds its critical angle of attack and lift drops sharply. It can occur at any speed or attitude, and recovery requires reducing the angle of attack by lowering the nose.

The angle between the wing chord line and the relative airflow. Lift increases with angle of attack up to the critical value, beyond which the wing stalls regardless of airspeed.

The drag created as a by-product of lift, caused by airflow around the wingtips. It increases with angle of attack and is greatest at low speed, which is why more power is needed to fly slowly.

The ratio of total lift to the aircraft's weight, expressed in g. It rises in turns and when pulling out of a dive, raising the stall speed and the structural stress on the airframe.

The point at which the aircraft's weight is considered to act. It must remain within a published range for stability and control, and moving it aft reduces longitudinal stability.

The calculation of total aircraft weight and centre of gravity position for a flight. It ensures the aircraft is within maximum weight limits and that handling and performance remain acceptable.

The difference between maximum structural take-off weight and the empty weight of the aircraft. It covers pilot, passengers, baggage, usable fuel and oil, and limits what can be carried.

The speed of the aircraft through the air mass, corrected for altitude and temperature effects on air density. It is used for navigation calculations and is higher than indicated airspeed at altitude.

The speed shown on the airspeed indicator, affected by air density and instrument and position error. Aircraft performance and limiting speeds are generally published in terms of indicated airspeed.

The aircraft's speed over the ground, equal to true airspeed corrected for wind. It is used to calculate time en route and fuel consumption for the flight.

A vector diagram combining the aircraft's heading and true airspeed with the wind direction and speed. It yields the resulting ground speed and the drift to apply to the true heading.

A navigation method that calculates position from a known starting point using heading, speed, time and wind. It must be updated with visual fixes or radio aids because errors accumulate.

The direction the aircraft's nose points, measured in degrees from a reference such as magnetic north. It differs from the track over the ground when the aircraft is drifting in wind.

The angle between true north and magnetic north at a given location, changing slowly over time. It must be applied when converting between true and magnetic directions for navigation and compass use.

The walk-around check of the aircraft before flight, covering structure, controls, fuel, oil, tyres and safety equipment against the checklist. It is the pilot's responsibility and must be completed before every flight.

Calculation of the fuel needed for taxi, trip, diversion and final reserve. The aircraft must carry at least the minimum required reserve, and the pilot must verify fuel quantity visually before departure.

A procedure in which an approach to land is abandoned and the aircraft climbs away. It is used when the approach is unstable or the runway is obstructed, and the pilot should decide early.

A standardised pattern flown around an aerodrome for take-off and landing, with defined legs and a standard turn direction. It keeps aircraft in predictable positions and reduces collision risk.

The pressure value entered in the altimeter subscale so that it indicates the desired reference, such as altitude above mean sea level. It must be updated as pressure changes or when crossing the transition altitude.

The aircraft system that supplies ram air pressure and static pressure to the airspeed indicator, altimeter and vertical speed indicator. Blockages cause erroneous readings, so covers and heaters are important.

A simple instrument showing magnetic heading using a magnetised card. It is subject to turning and acceleration errors and to deviation from aircraft magnetic fields, so it is used mainly as a standby reference.